Brooklyn Landlord-Tenant Lawyer, New York

A legal doctrine that prevents a plaintiff who has acted unethically in relation to a lawsuit from winning the suit or from recovering as much money as she would have if she had behaved honorably. For example, if a contractor is suing a homeowner to recover the price of work he did on the home, his failure to perform the work as specified would leave him with unclean hands.

A legal doctrine stating that if a person receives money or other property through no effort of his own, at the expense of another, the recipient should return the property to the rightful owner, even if the property was not obtained illegally. Most courts will order that the property be returned if the party who has suffered the loss brings a lawsuit.

A right to property that cannot be enforced in the present, but only at some time in the future. For example, John's will leaves his house to his sister Marian, but only after the death of his wife, Hillary. Marian has a future interest in the house.

A legally binding agreement involving two or more people or businesses (called parties) that sets forth what the parties will or will not do. Most contracts that can be carried out within one year can be either oral or written. Major exceptions include contracts involving the ownership of real estate and commercial contracts for goods worth $500 or more, which must be in writing to be enforceable. (See statute of frauds.) A contract is formed when competent parties -- usually adults of sound mind or business entities -- mutually agree to provide each other some benefit (called consideration), such as a promise to pay money in exchange for a promise to deliver specified goods or services or the actual delivery of those goods and services. A contract normally requires one party to make a reasonably detailed offer to do something -- including, typically, the price, time for performance and other essential terms and conditions -- and the other to accept without significant change. For example, if I offer to sell you ten roses for $5 to be delivered next Thursday and you say 'It's a deal,' we've made a valid contract. On the other hand, if one party fails to offer something of benefit to the other, there is no contract. For example, if Maria promises to fix Josh's car, there is no contract unless Josh promises something in return for Maria's services.

(1) A legal principle that prevents a person from asserting or denying something in court that contradicts what has already been established as the truth. equitable estoppelA type of estoppel that bars a person from adopting a position in court that contradicts his or her past statements or actions when that contradictory stance would be unfair to another person who relied on the original position. For example, if a landlord agrees to allow a tenant to pay the rent ten days late for six months, it would be unfair to allow the landlord to bring a court action in the fourth month to evict the tenant for being a week late with the rent. The landlord would be estopped from asserting his right to evict the tenant for late payment of rent. Also known as estoppel in pais.estoppel by deedA type of estoppel that prevents a person from denying the truth of anything that he or she stated in a deed, especially regarding who has valid ownership of the property. For example, someone who grants a deed to real estate before he actually owns the property can't later go back and undo the sale for that reason if, say, the new owner strikes oil in the backyard.estoppel by silenceA type of estoppel that prevents a person from asserting something when she had both the duty and the opportunity to speak up earlier, and her silence put another person at a disadvantage. For example, Edwards' Roofing Company has the wrong address and begins ripping the roof from Betty's house by mistake. If Betty sees this but remains silent, she cannot wait until the new roof is installed and then refuse to pay, asserting that the work was done without her agreement.estoppel in paisSee equitable estoppel.promissory estoppelA type of estoppel that prevents a person who made a promise from reneging when someone else has reasonably relied on the promise and will suffer a loss if the promise is broken. For example, Forrest tells Antonio to go ahead and buy a boat without a motor, because he will sell Antonio an old boat motor at a very reasonable price. If Antonio relies on Forrest's promise and buys the motorless boat, Forrest cannot then deny his promise to sell John the motor at the agreed-upon price.(2) A legal doctrine that prevents the relitigation of facts or issues that were previously resolved in court. For example, Alvin loses control of his car and accidentally sideswipes several parked cars. When the first car owner sues Alvin for damages, the court determines that Alvin was legally drunk at the time of the accident. Alvin will not be able to deny this fact in subsequent lawsuits against him. This type of estoppel is most commonly called collateral estoppel.

A statement included in a patent application that describes the structure of an invention in precise and exact terms, using a long established formal style and precise terminology. Patent claims serve as a way for the U.S. Patent and Trademark Office (PTO) to determine whether an invention is patentable, and as a way for a court to determine whether a patent has been infringed. In concept, a patent claim marks the boundaries of the patent in the same way as the legal description in a deed specifies the boundaries of the property.

A provision in a lease that absolves the landlord from responsibility for all damages, injuries or losses occurring on the property, including those caused by the landlord's actions. Most states have laws that void exculpatory clauses in rental agreements, which means that a court will not enforce them.